Search NASA⌕ Search

SEARCH · Search NASA

Results for “O&M”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Spectral methods in time for parabolic problems

A pseudospectral explicit scheme for solving linear, periodic, parabolic problems is described which has infinite accuracy both in time and in space. The high accuracy is achieved while the time resolution parameter M ( = ) (1/delta t) for time marching algorithm) and the space resolution parameter N B = O(1/detla x) have to satisfy M = O(N sup/+epsilon) epsilon O, compared to the common stability condition M = O(N sup 2) which has to be satisfied in any explicit finite order time algorithm.

Tal-Ezer, H.↗
NASA NTRS1992

ERS-1 SAR ice routing of l'Astrolabe through the Northeast passage

The use of Synthetic Aperture Radar (SAR) data from the satellite ERS-1 to assist the French polar vessel 'L'Astrolabe' during its navigation through Artic sea ice in the Northeast Passage is reported. The ship spent one month on the voyage from Europe to Japan, and high resolution SAR images and ice maps based on SAR images from ERS-1 and Special Sensor Microwave/Imager were telefaxed to the ship using the Inmarsat system. The time delay from observation to the reception of SAR images aboard the ship varied from 6 hours to two days. The quality of these ice maps was compared with Russian ice maps and observations from the ship. The SAR imagery provided detailed information on ice floe distribution, ice concentration, ice types, open leads, and tracks in ice from icebreakers. The response from the Russian ice specialists on the quality of the SAR ice maps was very positive.

Johannessen, O. M.↗
NASA NTRS1998

What the Polar Cap Tells Us about the Substorm Growth Phase

The polar cap region in the 30 to 60 minute period prior to the onset of the auroral substorm has been examined using global images from the Polar Ultraviolet Imager (UVI) to look for observational evidence of processes related to the substorm growth phase. In particular, the area of the polar cap has been measured to determine changes in its size in relation to the orientation of the interplanetary magnetic field (IMF). It was found that the size of the polar cap region increases during the growth phase even if the IMF has no southward component. Three phenomena have been observed to produce the increase in the size of the polar cap: (1) motion of the auroral oval to lower latitude, (2) thinning of the auroral oval, and (3) reduction of intense auroral precipitation in the polar cap region. The first phenomenon has been considered to be a result of the growth of the tail lobe magnetic field and the second is related to the thinning of the plasma sheet. Both of these have been supported by in situ observational evidence and are consistent with current models of substorm development. However, the third phenomenon appears to be unrelated to the first two and does not appear to be the result of opening of the polar cap flux tubes to the solar wind IMF. This reduction of auroral precipitation provides evidence of a growth phase process, or change in auroral precipitation processes, that is not explained by current substorm models.

Brittnacher, M. J.↗
NASA NTRS1998

Global Observation of Substorm Growth Phase Processes in the Polar Caps

Global images of the polar cap region during the substorm growth phase by the Polar Ultraviolet Imager reveals evidence of the processes which are not completely explained by current models. In particular, it was found that size of the polar cap region increases during the growth phase even if the interplanetary magnetic field has no southward component. Three phenomena were observed to produce an increase in the size of the polar cap: (1) motion of the auroral oval to lower latitude, (2) thinning of the auroral oval, and (3) reduction of intense aurora[ precipitation in the polar region. Correlation of image intensities with in situ particle measurements from the FAST satellite are being conducted to study the three growth phase phenomena; and to help identify the source regions of the particles, the mechanisms involved in producing the auroral structures and what may be reducing the polar cap precipitation during the substorm growth phase.

Brittnacher, M.↗
NASA NTRS1998

Extracellular calcium (Ca2+o)-sensing receptor in a mouse monocyte-macrophage cell line (J774): potential mediator of the actions of Ca2+o on the function of J774 cells

The calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays key roles in extracellular calcium ion (Ca2+o) homeostasis in parathyroid gland and kidney. Macrophage-like mononuclear cells appear at sites of osteoclastic bone resorption during bone remodeling and may play a role in the "reversal" phase following osteoclastic resorption and preceding bone formation. Bone resorption produces substantial local increases in Ca2+o that could provide a signal for bone marrow mononuclear cells in the vicinity, leading us to investigate whether such mononuclear cells express the CaR. In this study, we used the mouse J774 cell line, which exhibits a pure monocyte-macrophage phenotype. Both immunocytochemistry and Western blot analysis, using polyclonal antisera specific for the CaR, detected CaR protein in J774 cells. The use of reverse transcriptase-polymerase chain reaction with CaR-specific primers, including a set of intron-spanning primers, followed by nucleotide sequencing of the amplified products, also identified CaR transcripts in J774 cells. Exposure of J774 cells to high Ca2+o (2.8 mM or more) or the polycationic CaR agonist, neomycin (100 microM), stimulated both chemotaxis and DNA synthesis in J774 cells. Therefore, taken together, our data strongly suggest that the monocyte-macrophage cell line, J774, possesses both CaR protein and mRNA very similar, if not identical, to those in parathyroid and kidney.

NASA Discipline Musculoskeletal↗
NASA NTRSDate not supplied

Small-Sample Estimator Decisions – Certainly Uncertain in Human Spaceflight at NASA

Within statistics when estimating means, we rely heavily on the Central Limit Theorem (CLT) to aid in our inference, however in cases where the CLT does not apply we begin to be strongly limited in our choices. If a violation to the CLT comes in the form of small samples and unknown population variance, yet we maintain the assumption of normality, the use of t-distributions is perfectly valid. We explore cases where population normality is not assumed, where sample sizes are small, and where some actionable estimate of the central tendency of a distribution is needed such as for spaceflight operational decisions. Here we identify different scenarios based on measures taken from spaceflight, characterizing performance of estimators of central tendency within our set of simulations. We examine bias and variability of standard estimators of central tendency as they apply to varying small sample sizes and varying population distributions. Further work in this area is needed to develop a framework or set of guidelines for individuals set in these situations. Even with limited information, decisions need to be made.

Central Tendency↗
NASA NTRS2016

The Geology of Pluto and Charon Through the Eyes of New Horizons

NASA's New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto shows ongoing surface geological activity centered on a vast basin containing a thick layer of volatile ices that is involved in convection and advection, with a crater retention age no greater than 10 Ma. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic, and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to 4 Ga old that are extensionally fractured and extensively mantled and eroded by glacial or other processes. Charon is not currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest proposed impactor size-frequency distributions.

New Horizons spacecraft↗
NASA NTRS1991

Beta measurements

The second year's results of the BETA project research are presented. The program is divided into two areas, aerosol modification and climatology in the trade wind region and the climatology of BETA (CO2) on remote mountain top locations. Limited data is available on the aerosol climatology of the marine free troposphere (MFT) in the trade wind region. In order to study the effects of cumulus convection on the MFT values of BETA, a cloud model was developed to simulate the evolution of a typical Pacific trade wind cumulus cloud. The stages involved in this development are outlined. The assembly of the major optical components of the lidar was made. Tests were run of the spectral bandwidth of the Synrad laser when a portion of the beam is mixed with a component which has traveled 450 meters corresponding to a delay of 1.5 microsecs. The bandwidth of the beat signal was measured to be 3 KHz. The data processing system based on a parallel processing filter bank analyzer using true time squaring detectors at each filter was completed.

Schotland, R. M.↗
NASA NTRS1991

Demonstration of microwave power transmission in space

Three experiments are proposed to demonstrate the feasibility of converting dc power into microwave or millimeter-wave beam and transmitting it to users through free space. The generator could be located on earth or on a utility power satellite. The received power would be converted back into dc or ac power. The success of the experiments could lead to the commercial use of this technology.

Chang, K.↗
NASA NTRS1999

Evidence of Component Merging Equatorward of the Cusp

The Polar spacecraft passed through a region near the dayside magnetopause on May 29, 1996, at a geocentric distance of approx. 8 R (sub E) and high, northern magnetic latitudes. The interplanetary magnetic field (IMF) was northward during the pass. Data from the Thermal Ion Dynamics Experiment revealed the existence of low-speed (approx. 50 km s (exp-1)) ion D-shaped distributions mixed with cold ions (approx. 2 eV) over a period of 2.5 hours. These ions were traveling parallel to the magnetic field toward the Northern Hemisphere ionosphere and were convecting primarily eastward. The D-shaped distributions are distinct from a convecting Maxwellian and, along with the magnetic field direction, are taken as evidence that the spacecraft was inside the magnetosphere and not in the magnetosheath. Furthermore, the absence of ions in the antiparallel direction is taken as evidence that low-shear merging was occurring at a location southward of the spacecraft and equatorward of the Southern Hemisphere cusp. The cold ions were of ionospheric origin, with initially slow field-aligned speeds, which were accelerated upon reflection from the magnetopause. These observations provide significant new evidence consistent with component magnetic merging sites equatorward of the cusp for northward IMF.

Chandler, M. O.↗
NASA NTRS1998

Expression of extracellular calcium (Ca2 + o)-sensing receptor in the clonal osteoblast-like cell lines, UMR-106 and SAOS-2

The calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays key roles in extracellular calcium ion (Ca2 + o) homeostasis in parathyroid gland and kidney. More recent data have suggested the presence of this receptor in additional tissues, such as brain, intestine and skin. In this study, we examined the expression of the CaR in the rat and human osteosarcoma cell lines, UMR-106 and SAOS-2, respectively, which possess osteoblast-like characteristics. Both immunocytochemistry and Western blot analysis, using a polyclonal antiserum specific for the CaR, detected CaR protein in UMR-106 and SAOS-2 cells. The use of reverse transcription-polymerase chain reaction (RT-PCR) with CaR-specific primers, followed by nucleotide sequencing of the amplified products, also identified CaR transcripts in each cell line. Therefore, taken together, our data strongly suggest that the osteoblast-like cell lines, UMR-106 and SAOS-2, possess both CaR protein and mRNA very similar if not identical to those in parathyroid and kidney.

NASA Discipline Musculoskeletal↗
NASA NTRS2015

Supersonic Flight Dynamics Test: Trajectory, Atmosphere, and Aerodynamics Reconstruction

The Supersonic Flight Dynamics Test is a full-scale flight test of a Supersonic Inflatable Aerodynamic Decelerator, which is part of the Low Density Supersonic Decelerator technology development project. The purpose of the project is to develop and mature aerodynamic decelerator technologies for landing large mass payloads on the surface of Mars. The technologies include a Supersonic Inflatable Aerodynamic Decelerator and Supersonic Parachutes. The first Supersonic Flight Dynamics Test occurred on June 28th, 2014 at the Pacific Missile Range Facility. This test was used to validate the test architecture for future missions. The flight was a success and, in addition, was able to acquire data on the aerodynamic performance of the supersonic inflatable decelerator. This paper describes the instrumentation, analysis techniques, and acquired flight test data utilized to reconstruct the vehicle trajectory, atmosphere, and aerodynamics. The results of the reconstruction show significantly higher lofting of the trajectory, which can partially be explained by off-nominal booster motor performance. The reconstructed vehicle force and moment coefficients fall well within pre-flight predictions. A parameter identification analysis indicates that the vehicle displayed greater aerodynamic static stability than seen in pre-flight computational predictions and ballistic range tests.

Kutty, Prasad↗